Image Pickup Apparatus and Image Processing Method

1. An image pickup apparatus comprising: an image pickup device including a plurality of pixels arrayed in a two-dimensional form at a predetermined pixel pitch; a shooting mode setting section configured to set either one of a first shooting mode and a second shooting mode; a pixel shift section configured to, when the second shooting mode is set, perform a pixel shift so that a relative position in a direction of the array in the two-dimensional form between the image pickup device and a light flux received by the image pickup device becomes a plurality of relative positions, which differ in movement amounts, including a relative position in a movement amount which is a non-integral multiple of the pixel pitch; an image pickup control section configured to, when the first shooting mode is set, cause the image pickup device to perform an image pickup operation once to acquire one piece of image data, and when the second shooting mode is set, cause the image pickup device to perform the image pickup operation at the plurality of respective relative positions to acquire a plurality of pieces of image data; an image synthesis section configured to synthesize the plurality of pieces of image data acquired by the image pickup control section when the second shooting mode is set, to generate composite image data with a higher resolution than resolution of image data obtained from the image pickup device; a parameter determining section configured to, when the first shooting mode is set, determine a first parameter as an edge enhancement parameter, and when the second shooting mode is set, determine, as the edge enhancement parameter, a second parameter that provides a degree of edge enhancement higher than a degree of edge enhancement when the first parameter is used; and an image processing section configured to use the edge enhancement parameter determined by the parameter determining section, to perform edge enhancement processing for the one piece of image data when the first shooting mode is set, and to perform the edge enhancement processing for the composite image data when the second shooting mode is set.

2. The image pickup apparatus according to claim 1 , wherein the parameter determining section determines, as the edge enhancement parameter, the second parameter that compensates for an amount of decrease in pixel opening MTF characteristic caused by a pixel opening ratio becoming larger when the second shooting mode is set than when the first shooting mode is set.

3. The image pickup apparatus according to claim 1 , further comprising a memory configured to store the first parameter and the second parameter, wherein the parameter determining section, when the first shooting mode is set, receives an input of the first parameter from the memory and determines the first parameter as the edge enhancement parameter, and when the second shooting mode is set, receives an input of the second parameter from the memory and determines the second parameter as the edge enhancement parameter.

4. An image processing method for processing one piece of image data acquired, when a first shooting mode is set, by an image pickup device performing an image pickup operation once, the image pickup device including a plurality of pixels arrayed in a two-dimensional form at a predetermined pixel pitch, or a plurality of pieces of image data acquired, when the second shooting mode is set, by performing a pixel shift so that a relative position in a direction of the array in the two-dimensional form between the image pickup device and a light flux received by the image pickup device becomes a plurality of relative positions, which differ in movement amounts, including a relative position in a movement amount which is a non-integral multiple of the pixel pitch, and causing the image pickup device to perform the image pickup operation at the plurality of respective relative positions, the method comprising: for the one piece of image data acquired when the first shooting mode is set, determining a first parameter as an edge enhancement parameter, and performing edge enhancement processing for the one piece of image data using the edge enhancement parameter, for the plurality of image data acquired when the second shooting mode is set, synthesizing the plurality of pieces of image data to generate composite image data with a higher resolution than resolution of image data obtained from the image pickup device, determining, as the edge enhancement parameter, a second parameter that provides a degree of edge enhancement higher than a degree of edge enhancement when the first parameter is used; and performing the edge enhancement processing for the composite image data using the edge enhancement parameter.